Liver chemistries or liver functions tests are used to evaluate the health of your liver by measuring the levels of proteins, liver enzymes and bilirubin, a compound that functions as an antioxidant, in your blood. These tests basically try to measure certain enzymes and proteins in your blood to make sure their values are not too high or too low.

When Is a Liver Function Test Recommended?

If a patient has either hepatitis B or C, a liver function test may be recommended to check for liver infections. Sometimes this test is ordered by doctors to make sure certain prescribed medications aren’t adversely affecting the liver. They are also recommended for people who are already suffering from liver disease, so as to monitor their condition and also to check if the treatment they are receiving is working.

When patients begin to show symptoms of liver disease, a liver function test is recommended. Your doctor may even order it if you’re a heavy drinker or if you have gallbladder disease, or other medical conditions like diabetes, high blood pressure or anemia.

What Are the Most Common Liver Function Tests?

The most common tests used to check for liver abnormalities include:

–         ALT (Alanine Transaminase)

ALT is used to metabolize proteins. When a person’s liver is not working as it should, ALT is released into the bloodstream, causing its blood levels to rise. When this is tested for, high levels of ALT are detected in the blood, implying there is something wrong with liver function. A higher-than-normal result is mostly a sign of liver damage.

In females ALT above 25 international units per liter, and in males 33 international units per liter are higher than normal levels. If this occurs, it usually means more tests are required.

–         AST (Aspartate Aminotransferase)

AST is an enzyme that is found in parts of the body other than the liver as well, like the heart and muscles. On its own, AST is not enough to conclude whether there is liver damage or not. Therefore, levels of AST are always measured in conjunction with ALT. When the liver is indeed damaged, AST is released into the bloodstream as well, causing higher blood AST levels. It points either to liver damage or muscle damage.

The normal range for AST in adults is around 40 international units per liter and it tends to be higher in infants.

–         ALP (Alkaline Phosphatase)

ALP, also an enzyme, is found in the liver, in your bones and in bile ducts. ALP tests are also usually ordered in combination with a few other tests because on their own, they can’t do much in terms of conclusive evidence for liver damage. Higher-than-normal levels of ALP can either mean problems with the liver or bone disease.

It could also point to blocked bile ducts. Because children’s bodies are still growing, they tend to have higher levels of ALP but the normal range for adults is around 120 U/L. If an adult woman is pregnant, her normal ALP levels may be higher but otherwise, they should be around 120.

–         Albumin

Albumin is the main protein your liver makes and it carries out certain very important functions like nourishing your tissues, keeping fluid inside your vessels and transporting hormones and vitamins, among other substances, all over your body. When you get tested for albumin, what’s being tested is basically how well your liver is manufacturing this protein.

The normal ranges for albumin in the bloodstream are 3.5-5 grams per deciliter. If your albumin levels are low, it could be an indication of improper liver function, but also of a poor diet, kidney disease or some kind of infection or inflammation.

–         Bilirubin

Bilirubin is essentially a waste product produced by the body when red blood cells break down. But before being released as a stool, it passes through the liver where it is processed first. If the liver is damaged, it isn’t able to adequately eliminate the bilirubin from the body. This can result in higher-than-normal levels of bilirubin in the blood, indicating that the liver isn’t functioning properly.

The normal ranges for bilirubin in the blood are 0.1-1.2 mg per deciliter, which is a fairly low amount. However, abnormally high levels of bilirubin don’t always signal liver disease. Sometimes, people with normal liver function also have higher bilirubin levels, caused usually by some inherited disease.

Procedure and Risks

The doctor may ask you to fast before the test because certain food items and medications alter the levels of proteins that are checked for in these tests. However, you should drink enough water before the test, and wear a short-sleeved shirt so that drawing the blood sample is easier. The procedure is the same as a basic blood test, with potential risks of infection, hematoma or fainting.

To get your liver function test done or to learn more, consult with a specialist today.